EVAP System Pressure Sensor/Switch Circuit Range/Performance

What it means

The engine computer has detected that the fuel tank pressure sensor reading is electrically within limits but not plausible, such as not reading near atmospheric pressure when the system is open, or not changing when the EVAP valves operate. This usually points to a weak sensor or a blocked sensor port.

Related codes: P0450P0452P0453P0454P0446

Symptoms4

• Check engine light on.
• Usually no driving symptoms.
• Difficult refueling if a blocked vent is the cause.
• Failed emissions test.

Possible causes5

• Failed or drifting fuel tank pressure sensor.
• Sensor port or hose blocked by dirt or liquid fuel.
• Blocked vent or stuck vent valve causing real, unexpected pressure.
• Charcoal canister saturated with fuel from overfilling.
• High resistance in the wiring or connector.

How to diagnose5

1. Remove the fuel cap and watch the sensor reading; it should be close to atmospheric pressure per the manufacturer specification.
2. Command the purge and vent valves with a scan tool and watch the reading change.
3. Inspect the sensor hose and port for blockage or liquid fuel.
4. Inspect the vent opening and charcoal canister.
5. Check the connector and wiring for corrosion or high resistance.

How to fix5

1. Clean or replace a blocked sensor hose.
2. Clean the vent opening or replace a stuck vent valve.
3. Replace the charcoal canister if it is saturated with fuel.
4. Replace the tank pressure sensor if its reading stays implausible.
5. Clear the codes and drive until the EVAP self-test completes.

Repair cost

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low for a simple blockage or connector, and rises when the sensor or charcoal canister must be replaced, especially if the tank must be lowered.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions